This is called refraction. This can happen in raindrops ... So when the sun is behind you and the rain in front of you, you see a rainbow of colours reflected back from inside the raindrops.

This effect, called refraction, unravels the entire spectrum of visible light, which separates into distinct colours depending on the wavelength. The optical phenomenon is called a rainbow.

Viewers shared a few photos of the spectacle sight showing the double rainbow arching over stores and homes. Rainbows form when sunlight is scattered by water droplets through refraction.